﻿#region Copyright & License

//
// Author: Ian Davis <ian.f.davis@gmail.com> Copyright (c) 2007-2008, Ian Davs
//
// Portions of this software were developed for NUnit. See NOTICE.txt for more
// information. 
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//

#endregion

#region Using Directives

using System;
using System.Text.RegularExpressions;
using Ensurance.Properties;

#endregion

namespace Ensurance.Constraints.String
{
    /// <summary>
    /// RegexConstraint can test whether a string matches the pattern provided.
    /// </summary>
    public class RegexConstraint : Constraint<string>
    {
        private string _pattern;

        /// <summary>
        /// Initializes a new instance of the <see cref="RegexConstraint"/>
        /// class.
        /// </summary>
        /// <param name="pattern">The pattern.</param>
        public RegexConstraint(string pattern)
        {
            _pattern = pattern;
        }

        /// <summary>
        /// Test whether the constraint is satisfied by a given value
        /// </summary>
        /// <param name="actual">The value to be tested</param>
        /// <returns>True for success, false for failure</returns>
        public override bool IsSatisfiedBy(string actual)
        {
            Actual = actual;

            return actual is string &&
                   Regex.IsMatch(
                       (string)actual,
                       _pattern,
                       CaseInsensitive ? RegexOptions.IgnoreCase : RegexOptions.None);
        }

        /// <summary>
        /// Write the constraint description to a MessageWriter
        /// </summary>
        /// <exception cref="ArgumentNullException">if the message writer is null.</exception>
        /// <param name="writer">The writer on which the description is displayed</param>
        public override void WriteDescriptionTo(IMessageWriter writer)
        {
            if (writer == null)
            {
                throw new ArgumentNullException("writer");
            }

            writer.WritePredicate(Resources.StringMatching);
            writer.WriteExpectedValue(_pattern);
            if (CaseInsensitive)
            {
                writer.WriteModifier(Resources.IgnoringCase);
            }
        }
    }
}
